No it doesn't, not from CGI, they don't persist, try it, I just did , it didn't work :)

#!/usr/bin/perl --
##
##  printenv -- demo CGI program which just prints its environment
##


print "Content-type: text/plain; charset=iso-8859-1\n\n";


if( $ENV{QUERY_STRING} ){
    $ENV{OneTimeEnvTestWillItPersistProbablyNot}=1;
    print "so did OneTimeEnvTestWillItPersistProbablyNot persist? thou
+ght not\n\n\n";
} else {
    print "set OneTimeEnvTestWillItPersistProbablyNot=1\n";
    print "now append ?foo to the url to see if OneTimeEnvTestWillItPe
+rsistProbablyNot persists \n\n\n";
}

foreach $var (sort(keys(%ENV))) {
    $val = $ENV{$var};
    $val =~ s|\n|\\n|g;
    $val =~ s|"|\\"|g;
    print "${var}=\"${val}\"\n";
}
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